High silicon content monomers and polymers suitable for 193 nm bilayer resists

ABSTRACT

Polymerizable monomers having silicon containing groups that are transparent at 193 nm; and ethylenically unsaturated group are provided. Polymers from these monomers can be used in processes for forming sub-100 nm images with a chemically amplified, radiation sensitive bilayer resist. The bilayer resist is disposed on a substrate and comprises (i) a top imaging layer comprising a radiation sensitive acid generator and (ii) an organic underlayer. The bilayer resist can be used in the manufacturing of integrated circuits.

TECHNICAL FIELD

The present invention relates to new silicon containing monomers whichare transparent at 193 nm and copolymers obtained from these siliconcontaining monomers. The copolymers of the present invention areespecially suitable for forming radiation sensitive bilayer resists. Thebilayer resists can be used in the manufacture of integrated circuits.

BACKGROUND OF INVENTION

In the fabrication of integrated circuits, one of the more criticalprocedures is the lithographic processing. Improving lithographictechniques is a continuing demand in view of the ever increasing desirein the semiconductor industry for higher circuit density inmicroelectronic devices.

One method of achieving higher area density is to improve the resolutionof circuit patterns in resist films. It is known in the art thatincreasing the numerical aperture (NA) of the lens system of thelithographic imaging tool increases the resolution at a givenwavelength. However, increasing the NA results in a decrease in thedepth of focus (DOF) of the imaging radiation, thereby requiring areduction in the thickness of the imaging resist film. Further, theindustry wide shift to shorter wavelength exposure systems also resultsin as decrease in the DOF. A decrease in the resist film thickness canlead to problems in subsequent processing steps (e.g., ion implantationand etching).

In order to overcome these problems, bilayer resists have beendeveloped. Bilayer resists generally comprise a top thin film imaginglayer coated on a thick organic underlayer. The resist is patterned by(i) imagewise exposure and development of the top layer, and then (ii)anisotropically transferring the developed pattern in the top layerthrough the thick underlayer to the substrate. Suitably, the top layercontains precursors to refractory oxides such as silicon, boron, orgermanium which enable the use of oxygen-reactive ion etching (RIE) inthe image transfer step.

Bilayer resists are known in the art, however, these resists weregenerally developed before the advent of deep U.V. lithography (e.g.,248 nm and 193 nm) and are of little utility for high resolutionimaging. The silicon containing bilayer photoresists are one of the moreattractive candidates for possible use for 248 nm applications. There iscurrently a need to develop materials for the next generation ofexposure systems at 193 nm (and perhaps 157 nm) as well. Unfortunatelycurrent generation DUV bilayer resists are not extendible to shorterwavelengths due to poor transparency at these shorter wavelengths. Thishigh absorbance is due in large part to the aromaticpoly(hydroxystyrene) moiety found in nearly all DUV 248 nm resists.However, certain structural types of silicon monomers can alsocontribute to the high absorbance at 193 nm. For example, the 4SiMAmonomer (see FIG. 1), a tetrasilane containing Si—Si linkages, isdisclosed in U.S. Pat. No. 5,985,524, inter alia, for use in bilayerresists. This is a very useful bilayer resist component due to its highsilicon density and correspondingly high O2-RIE etch resistance atrelatively low monomer loadings. Low silicon monomer loadings aregenerally desirable since silicon often negatively impacts the resistdissolution characteristics. Low loadings also provide greater latitudein the design of the polymer.

Unfortunately, the presence of Si—Si bonding in this monomer leads tounacceptably high absorbance at 193 nm. For example, a methacrylatepolymer containing only 20 mole percent of this monomer (see FIG. 2;other monomers in this polymer are nearly transparent) has an absorbanceof 6 per micron film, which makes this monomer unsuitable for 193 nmapplications.

It has also been suggested to use a commercially available Si—O—Sicontaining monomer (see FIG. 3) in 193 nm bilayer resist development.See Schaedeli et al., “Bilayer Resist Approach for 193 nm Lithography”,Proc. SPIE, Vol. 2724, pp. 344-354, 1996. However, the introduction ofsilicon-oxygen functionality into the monomer can have deleteriousconsequences on the resist performance. Particularly, these siloxanesoften have poor hydrolytic stability under the processing conditionsemployed in these chemically amplified resists. This in turn can resultin crosslinking reactions which can negatively impact the dissolutionproperties. In some cases, crosslinking occurring during the polymerpreparation have been observed.

More recently, Kessel et al, “Novel Silicon-Containing Resists for EUVand 193 nm Lithography”, Proc. SPIE, Vol. 3678, pp. 214-220, 1999describe a bilayer resist claiming to be suitable for 193 nm resistapplications. However, the polymer in this resist (see FIG. 6) containsa silicon containing monomer with Si—Si linkages similar to monomers inU.S. Pat. No. 5,989,524. As stated above, this 4Si group absorbsstrongly at 193 nm, making it unsuitable for 193 nm resist applications(see FIG. 4 in reference 3 for examples of the poorly defined imagesthat are a consequence of high polymer absorption). It is therefore anobject of the present invention to provide an improved 193 nm bilayerresist. Other objects and advantages will become apparent from thefollowing disclosure.

SUMMARY OF INVENTION

The present invention relates to new polymerizable monomers havingsilicon containing groups separated from each other by a group X whereinthe group X is non-reactive and is transparent at 193 nm, and containingpolymerizable ethylenically unsaturated group.

The present invention also relates to polymers from (a) a polymerizablemonomer having silicon containing groups separated from each other by agroup X wherein the group X is non-reactive and is transparent at 193nm, and containing polymerizable ethylenically group.

A still further aspect of the present invention is concerned with aprocess for generating a bilayer resist image on a substrate. Theprocess comprises:

(a) coating a substrate with an organic underlayer;

(b) coating the organic underlayer with a top layer comprising:

(i) a radiation sensitive acid generator and

(ii) a polymer from a polymerizable monomer having silicon containinggroups separated from each other by a group X wherein the group X isnon-reactive and is transparent at 193 nm, and containing polymerizableethylenically unsaturated group, and being acid labile;

(c) imagewise exposing the top layer to radiation;

(d) developing the image in the top layer; and

(e) transferring the image through the organic underlayer to thesubstrate.

Still other objects and advantages of the present invention will becomereadily apparent by those skilled in the art from the following detaileddescription, wherein it is shown and described preferred embodiments ofthe invention, simply by way of illustration of the best modecontemplated of carrying out the invention. As will be realized theinvention is capable of other and different embodiments, and its severaldetails are capable of modifications in various obvious respects,without departing from the invention. Accordingly, the description is tobe regarded as illustrative in nature and not as restrictive.

SUMMARY OF DRAWINGS

FIGS. 1, 2, 3 and 6 illustrate structures of silicon monomers notexhibiting the advantages achievable by the present invention.

FIGS. 4 and 8 illustrate the structure of a monomer within the scope ofthe present invention.

FIGS. 5 and 7 illustrate structures of copolymers of the presentinvention.

FIG. 9 illustrates structures of inactive silicon containing monomerssuitable for use in the present invention.

BEST AND VARIOUS MODES FOR CARRYING OUT INVENTION

The polymerizable monomers of the present invention are capable ofproviding positive tone, chemically amplified polymer resists suitablefor 193 nm applications.

The silicon-containing monomers of the present invention contain a groupX that is non-absorbing at 193 nm and an ethylenically unsaturatedgroup. The silicon containing monomers are either acid labile (active)or acid-stable (inactive). The group X is preferably an alkylene (CR₂)ngroup wherein n is typically an integer of 1 to 4 and more typically 1to 2. The bridging alkylene group is important in that it enables themonomer to be transparent at 193 nm. These silicon-containing monomersinclude acid-labile (active) (FIG. 8) and acid-stable (inactive) (FIG.9) monomers. The acid labile monomers can have a two-carbon unit betweenthe silicon and oxygen; whereas, the acid stable monomers can haveeither one carbon atom or three or more carbon atoms between siliconand, oxygen. As shown in FIG. 8, the acid labile monomers can also havea tertiary carbon atom attached to an ester oxygen, and the tertiarycarbon is between a silicon atom and the ester oxygen. As shown in FIG.9, the acid stable monomer can be void of any ester oxygen linking thesilicon atom.

The ethylenically unsaturated portion of the monomer is typically froman acrylate, methacrylate, or cyclic-olefin.

The silicon containing polymers of the present invention can be used asa homopolymer or can be a copolymer. Suitable comonomers includeacrylate, methacrylate, cyclic-olefin, maleic anhydride, and itaconicanhydride may contain in addition to active and inactive silicon groups,functional groups such as tertiary alkyl esters (t-butyl esters),actals, ketals and other acid labile groups. Preferably, the polymercontains two silicon containing monomers, one inactive and one active(acid labile). They may also contain polar groups such as carboxylicacids, sulfonamides, fluorinated alcohols.

The polymers typically have number average molecular weights of about1000 to about 10,000, and more typically about 3000 to about 5000.

Copolymers typically contain about 10 to about 50 mol % of the acidlabile silicon containing monomer and about 50 to about 90 mol % of theother monomer(s). When the inactive silicon monomer is present, such istypically employed in amounts of about 10 to about 40 mol %. When usedin a bilayer resist, the polymers of the present invention are used asthe top imaging layer along with a radiation sensitive acid generator.

In an alternative embodiment, the top layer contains monomeric orpolymeric dissolution inhibitors in addition to the polymer. Thedissolution inhibitors may contain silicon containing groups, bothactive and inactive.

The second component of the top imaging layer is the radiation sensitiveacid generator. Upon exposure to radiation, the radiation sensitive acidgenerator generates a strong acid. Suitable acid generators includetriflates (e.g. triphenylsulfonium triflate or bis-(t-butyl phenyl)iodonium triflate), pyrogallol (e.g. trimesylate of pyrogallol),perfluoroalkane sulfonates, bis-(t-butyl phenyl) iodoniumperfluorooctane sulfonate), onium salts such as triarylsulfonium anddiaryliodonium hexafluoroantimonates, hexafluoroarsenates, and others;trifluoromethane sulfonate esters of hydroxyimides,alpha-alpha′-bis-sulfonyl diazomethanes, sulfonate esters ofnitro-substituted benzyl alcohols and naphthoquinone-4-diazides andalkyl disulfones. Other suitable photoacid generators are disclosed inAllen U.S. Pat. Nos. 5,045,431 and 5,071,730 and Reichmanis et al,Chemistry of Materials, Vol. 3, page 395 (1991), the disclosures ofwhich are incorporated herein by reference for all purposes.

The two component top imaging layer generally comprises about 1 to 10weight percent of the acid generator and about 90 to 99 weight percentof the polymer. The top imaging layer may optionally comprise otherminor components such as dissolution inhibitors, coating enhancers,surfactants, bases and other compounds known to those skilled in theart. When employed, the dissolution inhibitors are present in amounts ofabout 1 to about 15% by weight based upon the total weight of thepolymer and dissolution inhibitor. Typical dissolution inhibitors arebile-acid esters (e.g. cholate esters). See U.S. Pat. No. 5,580,694, andWallow et al, Proc. SPIE, 2724, 335, 1996, disclosures of which areincorporated herein by reference.

Suitable organic, polymeric, planarizing underlayers for the resist ofthe present invention include cross-linked poly(hydroxystyrene),polyesters, polyacrylates, cyclic-olefin polymers and the like.

The present invention relates to a process for generating a positivebilayer resist image on a substrate comprising the steps of (a) coatinga substrate with an organic underlayer; (b) coating the organicunderlayer with a top layer comprising a radiation sensitive acidgenerator and a polymer having silicon containing groups some of whichare acid labile; (c) imagewise exposing the top layer to radiation; (d)developing the image in the top layer; and (e) transferring the imagethrough the organic underlayer to the substrate.

The first step of the process of the present invention involves coatingthe substrate with a layer comprising an organic polymer dissolved in asuitable solvent. Suitable substrates are comprises of silicon. Suitablesolvents for the organic polymer underlayer include propylene glycolmonomethyl ether acetate, ethyl lactate and cyclohexanone. The layer canbe coated on the substrate using art-known techniques such as spin orspray coating or doctor blading. The layer is then heated to an elevatedtemperature of about 100-250° C. for a short period of time of about1-30 minutes to drive off solvent and optionally thermally inducecrosslinking. The dried underlayer typically has a thickness of about0.5-20 microns, and more typically about 1 micron.

In the second step of the process, the components of the top imaginglayer are dissolved in a suitable solvent such as propylene glycolmonomethyl ether acetate and ethyl lactate. It is desired that theimaging layer not admix with the underlayer during the coating process.The top layer typically has a thickness of about 0.1 to 0.3 microns.

In the next step of the process, the film is imagewise exposed toradiation (UV, X-ray, e-beam, EUV), typically ultraviolet radiationsuitably at a wavelength of about 190-365 nm (193/248/254/365),preferably 193 or 248 nm. Suitable radiation sources include mercury,mercury/xenon, and xenon lamps. The preferred radiation is ArF excimerlaser or KrF excimer laser. At longer wavelengths (e.g. 365 nm) asensitizer may be added to the top imaging layer to enhance absorptionof the radiation. Conveniently, due to the enhanced radiationsensitivity of the top layer of the resist film, the top layer of thefilm is fully exposed with less than about 100 mJ/cm² of radiation, morepreferably less than about 50 mJ/cm². The radiation is absorbed by theradiation sensitive acid generator to generate free acid which causescleavage of the silicon containing acid labile group and the formationof the corresponding carboxylic acid.

Preferably, after the film has been exposed to radiation, the film isagain heated to an elevated temperature of about 130° C. for a shortperiod of time of about 1 minute.

The next step involves development of an image in the top layer with asuitable developer. Suitable developers for development of a positiveimage include an aqueous base, preferably a metal ion free aqueous basesuch as tetramethyl ammonium hydroxide or chlorine. The developmentresults in the removal of the exposed areas of the top layer of thefilm.

The last step of the process involves transferring of the developedimage in the top layer through the underlayer to the substrate by knowntechniques. Preferably, the image is transferred by etching withreactive ions such as oxygen plasma, oxygen/sulfur dioxide plasma.Suitable plasma tools include electron cyclotron resonance (ECR),helicon, inductively coupled plasma (ICP) and transmission-coupledplasma (TCP) systems. Etching techniques are well known in the art andequipment is commercially available to etch films.

The bilayer resist of the present invention may be used to make anintegrated circuit assembly, such as an integrated circuit chip,multichip modules or circuit board. The integrated circuit assemblycomprises a circuit formed on a substrate by using the process of thepresent invention and then additionally forming a circuit in thedeveloped film on the substrate by art-known techniques. After thesubstrate has been exposed, circuit patterns can be formed in theexposed areas by coating the substrate with a conductive material suchas conductive metals by art-known dry-etching techniques such asevaporation, sputtering, plating, chemical vapor deposition, orlaser-induced deposition. The surface of the film can be milled toremove any excess conductive material. Dielectric materials may also bedeposited by similar means during the process of making circuits.Inorganic ions such as boron, phosphorous, or arsenic can be implantedin the substrate in the process for making p- or n-doped circuittransistors. Other means for forming circuits are well known to thoseskilled in the art.

The following non-limiting examples are detailed descriptions of methodsof preparation and use of the resist of the present invention. Thedetailed preparations fall within the scope of, and serve to exemplifythe more generally described methods set forth above. The examples arepresented for illustrative purposes only, and are not intended as arestriction on the scope of the invention.

EXAMPLE 1

Synthesis of Bis(trimethylsilyl)methylmethacrylate

Bis(trimethylsilyl)chloromethane (Aldrich) (14.68 g, 0.075 mole), sodiummethacrylate (8.96 g, 0.0825 mole), Adogen 464 (Aldrich) (1.70 g), andphenothiazine (0.05 grams) were placed in a round bottom flask equippedwith a condenser, mechanical stirrer and a nitrogen inlet. The flask wascharged with 200 ml acetonitrile and heated to reflux while stirring.After 4 days, the mixture was filtered to remove the solids and thesolvent was removed in a rotary evaporator. Fractional distillationunder reduced pressure gave 10.90 grams (60% yield) of a clear liquid at46-48° C. at 0.5 mm pressure.

EXAMPLE 2

Synthesis of 2-Trimethylsilylethylmethacrylate

2-Trimethylsilylethanol (Aldrich) (30 g, 0.25 mole) was placed in around bottom flask equipped with a condenser, addition funnel, magneticstirrer and a nitrogen inlet. 200 ml dichloromethane, pyridine (20.80 g,0.26 mole) and 100 mg of phenothiazine were added to the flask. Whilestirring, methacryloyl chloride (27.18 g, 0.26 mole) in 100 mldichloromethane was added dropwise at room temperature. A mildlyexothermic reaction occurred. The mixture was stirred overnight at roomtemperature. Afterwards, the mixture was washed with 1×100 ml deionizedwater and 2×100 ml brine and dried over anhydrous magnesium sulfate. Thesolution was concentrated in vacuo. Fractional distillation underreduced pressure gave 20.82 grams of the desired product at 35-38° C. at0.5 mm.

EXAMPLE 3

Synthesis of a Terpolymer Comprising Bis(trimethylsilyl)methylMethacrylate, 2-trimethylsilylethyl Methacrylate, and Itaconic Anhydride

Bis(trimethylsilyl)methyl methacrylate (2.44 g, 0.01 mole),2-trimethylsilylethyl methacrylate (2.80 g, 0.025 mole), and itaconicanhydride (2.80 g, 0.025 mole) were placed with 25 ml of tetrahydrofuran(THF) in a round bottom flask equipped with a condenser and a nitrogeninlet. Azoisobutyronitrile (AIBN) (0.33 g) was added to this solutionand stirred until dissolved. Then the solution was evacuated with theaid of a Firestone valve and purged with nitrogen four times. Thecontents were then heated to reflux for 18 hours. Afterwards, thesolution was diluted with acetone (20 ml) and added dropwise intohexanes (800 ml). The precipitated polymer was filtered (frit), washedtwice with hexanes (50 ml) dried under vacuum at 60° C. Yield: 5.6grams. Mw=13,000.

EXAMPLE 4

Synthesis of Bis(trimethylsilyl)methylacrylate

Bis(trimethylsilyl)chloromethane (Aldrich) 39 g, 0.2 mole), sodiumacrylate (28 g, 0.3 mole), Adogen 464 (Aldrich) (6.96 g), andphenothiazine (0.10 grams) were placed in a round bottom flask equippedwith a condenser, mechanical stirrer and a nitrogen inlet. The flask wascharged with 100 ml of butyronitrile and heated to reflux whilestirring. After 6 hours, the mixture was diluted with 150 ml hexanes andfiltered to remove the solids. The solvents were removed under reducedpressure. Fractional distillation of the residue under reduced pressuregave 35.5 grams 975%) of the desired product at 45-58° C. at 0.5 mmpressure.

EXAMPLE 5

Synthesis of Bis(trimethylsilyl)methyl 5-Norbornene-2-carboxylate (FIG.9, Top Row #2)

A 100 mL three-neck round-bottom flask was equipped with a thermocouplethermometer, magnetic stirrer, addition funnel with nitrogen attachment,and an ice-water cooling bath. The flask was charged with 19 grams(0.287 mol) of freshly distilled cyclopentadiene. The addition funnelwas charged with 60 grams (0.26 mol) of bis(trimethylsilyl)methylacrylate which was added to the cyclopentadiene with stirring,maintaining the temperature between 0 and 10° C. After the addition wascompleted the reaction was allowed to warm to room temperature and stirovernight. The reaction was distilled under vacuum collecting thefraction boiling at 98-101° C. at 100 milliTorr to yield 61 grams ofproduct.

EXAMPLE 6

Synthesis of 2-(2-Methyl-4-trimethylsilyl)butyl5-Norbornene-2-carboxylate (FIG. 8, Second Row #2)

Step 1: Synthesis of 2-methyl-4-trimethylsilyl-2-butanol

A 250 mL 3-neck round-bottom flask was equipped with a magnetic stirrer,dry-ice condenser with a nitrogen bubbler, thermocouple thermometer, icewater cooling bath, and a gas inlet tube attached through a back flowtrap to a cylinder of trimethylsilane. The flask was charged with 68.9 g(0.80 mol) of 2-methyl-3-buten-2-ol and 600 mg of platinum-divinyltetramethyl disiloxane complex in toluene (about 2 mol % platinum) andcooled to below 10° C. The reaction temperature was maintained between 5and 10° C. as the silane (63 grams, 0.85 mol) was added slowly over 3hours. The ice-water cooling bath was removed but the dry-ice condenserwas maintained with dry-ice while stirring overnight. The condenser wasremoved and replaced with a distillation apparatus and the reactionmixture distilled under vacuum. The major fraction distilling at105-108° C. at 200 milliTorr was collected, yielding 124 grams ofproduct.

Step 2: Synthesis of 5-Norbornene-2-carbonylchloride

A 1 liter, three-neck round bottom flask equipped with a magneticstirrer, thermocouple thermometer, glass stopper, addition funnel withnitrogen gas purge, and a dry-ice cooling bath was charged with 248grams (3.75 mol) of freshly distilled cyclopentadiene which was cooledto 0° C. The addition funnel was charged with 316.8 grams (3.5 mol) ofdistilled acryloyl chloride which was added dropwise to the reactionover three hours while maintaining the reaction temperature between 0and 10° C. After the acryloyl chloride addition was complete, thecooling bath was removed and the reaction allowed to warm to roomtemperature overnight. The reaction mixture was distilled under vacuumcollecting 533 grams of product distilling at 54-56° C. at a pressure of300 milliTorr.

Step 3: Synthesis of 2-(2-Methyl-4-trimethylsilyl)butyl5-Norbornene-2-carboxylate

A 2 liter, three-neck round-bottom flask equipped with a mechanicalstirrer, thermocouple thermometer, addition funnel with a nitrogeninlet, and an ice-water bath was charged with 124 grams (0.775 mol) of2-methyl-4-trimethylsilyl-2-butanol, 98 grams (0.969 mol) oftriethylamine and 1 liter of anhydrous methylene chloride and cooled tobelow 10° C. The addition funnel was charged with 139.4 grams (0.89 mol)of norbornene-2-carbonylchloride which was added dropwise to the stirredreaction mixture while maintaining the internal reaction temperaturebelow 10° C. The dark reaction mixture was allowed to warm to roomtemperature and stir overnight. The addition funnel was charged with 20mL of water which was added dropwise to the stirred reaction. Afterstirring for several hours, the reaction mixture was evaporated, takenup in diethylether and filtered. The filtrate was washed two times withwater, one with brine, dried over anhydrous sodium sulfate and thenfiltered and evaporated. The residue was distilled under vacuum to yield159 grams of product distilling at 110-115° C. at a pressure of 300milliTorr.

EXAMPLE 7

Synthesis of a Terpolymer (FIG. 7) Comprising Bis(trimethylsilyl)methyl5-Norbornene-2-carboxylate (FIG. 9, Top Row #2),2-(2-Methyl-4-trimethylsilyl)butyl 5-Norbornene-2-carboxylate (FIG. 8,Bottom Row #2), and Maleic Anhydride

Bis(trimethylsilyl)methyl 5-Norbornene-2-carboxylate (5.93 g, 0.02mole), 2-(2-methyl-4-trimethylsilyl)butyl 5-Norbornene-2-carboxylate(11.2 g, 0.04 mole) and freshly sublimed maleic anhydride (7.19 g, 0.073mole) were placed with 28 ml of anhydrous ethylacetate in a round bottomflask equipped with a condenser and a nitrogen inlet.Azoisobutyronitrile (AIBN) (0.88 g) was added to this solution andstirred until dissolved. Then the solution was evacuated with the aid ofa Firestone valve and purged with nitrogen four times. The contents werethen heated to reflux for 18 hours. Afterwards, the solution was addeddropwise into petroleum ether (35-60° C.) (1200 ml). The precipitatedpolymer was filtered (frit), washed twice with petether (50 ml) anddried under vacuum at 60° C. Yield: 13.0 grams. Mw=7000.

EXAMPLE 8

Synthesis of an Underlayer Polymer:Poly(Para-hydroxystyrene-co-epoxydicyclopentadiene Methacrylate (30:70)

A 500 mL round bottom flask was equipped with a magnetic stirrer,thermocouple thermometer, condensor with nitrogen gas bubblerattachment, and a temperature-controlled heating mantle. The flask wascharged with 33.58 grams of 35.45 weight percent para-hydroxystyrene indiethylene glycol (11.9 grams para-hydroxystyrene), 54.09 grams ofepoxydicyclopentadiene methacrylate, and 214 mL of isopropanol. Thestirred mixture was heated to reflux, then 2.15 grams of2,2′-azobisisobutyronitrile was added and the reaction vessel flushedwith nitrogen. The mixture was kept under nitrogen and refluxed for 19hours. The reaction mixture was then diluted with 200 mL of acetone andprecipitated into 6 liters of rapidly stirred hexane. The solid productwas filtered, washed with two 200 mL portions of hexane, and dried. Thedried solid was suspended with stirring in a mixture of 3.5 liters ofwater and 200 mL of acetone for 4 hours. The solid was filtered and thewater/acetone wash process repeated two more times. The solid wasfiltered and dried under vacuum to yield 58.0 grams of polymer.Mw=11,600.

EXAMPLE 9

193 nm Organic Underlayer Formulation

The above underlayer polymer (R—OH) (4 grams) and a thermal acidgenerator, di(t-butyl)iodonium perfluorooctane sulfonate (200 mg), weredissolved in a mixture of propylene glycol monomethyl ether acetate (16grams) and cyclohexanone (4 grams).

EXAMPLE 10

193 nm Bilayer Resist Formulation (Top Imaging Layer)

Several bilayer resists were formulated. Typically, the formulationcontains 95 weight percent of the bilayer polymer and 5 weight percentof a photoacid generator, di(t-butyl) iodonium perfluoroctane sulfonate,in propylene glycol monomethyl ether acetate.

EXAMPLE 11

193 nm Bilayer Resist Evaluation

A silicon substrate was coated with 0.6 microns of the organicunderlayer and baked at 225° C. for 2 minutes. The underlayer wasovercoated with 1500 Å of a top imaging layer composition comprisingabout 95 weight percent of the terpolymer in example 7 and 5 weightpercent of a photoacid generator (di(t-butyl) iodonium perfluorooctanesulfonate. the films were baked at 130° C. for 1 minute to drive thesolvent out. The films were then imagewise exposed at 193 nm (dose15-100 mJ/cm²). The film was then baked at 130° C. for 1 minute and thetop layer was developed with 0.263 N tetramethyl ammonium hydroxide.Very high resolution images were obtained with this resist. 70 nm (1:2line/space) patterns were resolved when exposed through an alternatingphase shift mask. The images were straight walled and without anyresidue.

The foregoing description of the invention illustrates and describes thepresent invention. Additionally, the disclosure shows and describes onlythe preferred embodiments of the invention but, as mentioned above, itis to be understood that the invention is capable of use in variousother combinations, modifications, and environments and is capable ofchanges or modifications within the scope of the inventive concept asexpressed herein, commensurate with the above teachings and/or the skillor knowledge of the relevant art. The embodiments described hereinaboveare further intended to explain best modes known of practicing theinvention and to enable others skilled in the art to utilize theinvention in such, or other, embodiments and with the variousmodifications required by the particular applications or uses of theinvention. Accordingly, the description is not intended to limit theinvention to the form disclosed herein. Also, it is intended that theappended claims be construed to include alternative embodiments.

What is claimed is:
 1. A process for generating a bilayer resist imageon a substrate comprising: (a) coating a substrate with an organicunderlayer; (b) coating the organic underlayer with a top layercomprising: (i) a radiation sensitive acid generator and (ii) a polymerpolymerized from a silicon-containing monomer that is acid-labile and asilicon-containing monomer that is acid-stable, and the acid-stable thesilicon monomers containing an ethylenically unsaturated group, monomerhas a silicon atom separated from an ester oxygen by one methylenecarbon atom, or is void of any ester oxygen linking the silicon atom;(c) imagewise exposing the top layer to radiation; (d) developing theimage in the top layer; and (e) transferring the image through theorganic underlayer to the substrate.
 2. The process of claim 1 whereinthe polymer is polymerized from more than one silicon-containing monomerthat is acid-labile.
 3. The process of claim 1 wherein the polymer ispolymerized from more than one acid-stable silicon monomer and more thanone acid-labile silicon monomer.
 4. The process of claim 1 wherein thepolymer has polar groups.
 5. The process of claim 1 wherein the acidgenerator is selected from perfluoroalkane sulfonates, onium salts,trifluoromethane sulfonate esters of hydroxyimides,alpha-alpha′-bis-sulfonyl diazomethanes, sulfonate esters ofnitro-substituted benzyl alcohols and of naphthoquinone-4-diazides andalkyl disulfones.
 6. The process of claim 1 wherein the top layer isimagewise exposed to radiation having a wavelength of 193 nm.
 7. Theprocess of claim 1 wherein the top layer is imagewise exposed toradiation having a wavelength of 248 nm.
 8. The process of claim 1,wherein the underlayer is an organic polymer comprising one or more ofthe monomers selected from the group consisting of acrylate,cyclic-olefin, hydroxystyrene, and epoxy monomers.
 9. The process ofclaim 1 wherein the top layer further comprises a dissolution inhibitor.10. The process of claim 9 wherein the dissolution inhibitor containssilicon.
 11. The process of claim 1 wherein the ethylenicallyunsaturated group is selected from the group consisting of acrylate,methacrylate, and cyclic olefin.
 12. The process of claim 11 wherein thecyclic olefin is norbornene.
 13. The process of claim 1 wherein thepolymer is polymerized in the presence of one or more comonomersselected from the group consisting of acrylate, methacrylate, cyclicolefin, maleic anhydride, and itaconic anhydride.
 14. The process ofclaim 1 wherein the silicon-containing monomer that is acid-labilecontains more than one silicon group that is acid-labile.
 15. Theprocess of claim 1 wherein the silicon-containing monomer that isacid-stable contains more than one silicon group that is acid-stable.16. The process of claim 1 wherein the acid-labile monomer has atwo-carbon ethylene unit between a silicon atom and an ester oxygen. 17.The process of claim 16 wherein the acid-stable monomer is void of anyester oxygen linking the silicon atom.
 18. The process of claim 16wherein the acid-stable monomer has one methylene carbon atom betweenthe silicon atom and the ester oxygen.
 19. The process of claim 1wherein the acid-labile monomer has a tertiary carbon atom attached toan ester oxygen, and the tertiary carbon is between a silicon atom andthe ester oxygen.
 20. The process of claim 19 wherein the acid-stablemonomer is void of any ester oxygen linking the silicon atom.
 21. Theprocess of claim 19 wherein the acid-stable monomer has one methylenecarbon atom between the silicon atom and the ester oxygen.
 22. A processfor generating a bilayer resist image on a substrate comprising: (a)coating a substrate with an organic underlayer; (b) coating the organic;underlayer with a top layer comprising: (i) a radiation sensitive acidgenerator and (ii) a polymer polymerized from a silicon-containingmonomer that is acid-labile and a silicon-containing monomer that isacid-stable, wherein the polymer is polymerized from more than onesilicon-containing monomer that is acid-labile; (c) imagewise exposingthe top layer to radiation; (d) developing the image in the top layer;and (e) transferring the image through the organic underlayer to thesubstrate.
 23. A process for generating a bilayer resist image on asubstrate comprising: (a) coating a substrate with an organicunderlayer; (b) coating the organic underlayer with a top layercomprising: (i) a radiation sensitive acid generator and (ii) a polymerpolymerized from a silicon-containing monomer that is acid-labile and asilicon-containing monomer that is acid-stable, wherein the polymer ispolymerized from more than one acid-stable silicon monomer and more thanone acid-labile silicon monomer; (c) imagewise exposing the top layer toradiation; (d) developing the image in the top layer; and (e)transferring the image through the organic underlayer to the substrate.24. A process for generating a bilayer resist image on a substratecomprising: (a) coating a substrate with an organic underlayer; (b)coating the organic underlayer with a top layer comprising: (i) aradiation sensitive acid generator and (ii) a polymer polymerized from asilicon-containing monomer that is acid-labile and a silicon-containingmonomer that is acid-stable, wherein the silicon monomers contain anorbornene group; (c) imagewise exposing the top layer to radiation; (d)developing the image in the top layer; and (e) transferring the imagethrough the organic underlayer to the substrate.
 25. A process forgenerating a bilayer resist image on a substrate comprising: (a) coatinga substrate with an organic underlayer; (b) coating the organicunderlayer with a top layer comprising: (i) a radiation sensitive acidgenerator and (ii) a polymer polymerized from a silicon-containingmonomer that is acid-labile and a silicon-containing monomer that isacid-stable, wherein the silicon-containing monomer that is acid-labilecontains more than one silicon group that is acid-labile; (c) imagewiseexposing the top layer to radiation; (d) developing the image in the toplayer; and (e) transferring the image through the organic underlayer tothe substrate.
 26. A process for generating a bilayer resist image on asubstrate comprising: (a) coating a substrate with an organicunderlayer; (b) coating the organic underlayer with a top layercomprising: (i) a radiation sensitive acid generator and (ii) a polymerpolymerized from a silicon-containing monomer that is acid-labile and asilicon-containing monomer that is acid-stable, wherein thesilicon-containing monomer that is acid-stable contains more than onesilicon group that is acid-stable; (c) imagewise exposing the top layerto radiation; (d) developing the image in the top layer; and (e)transferring the image through the organic underlayer to the substrate.